Analysis of information sources in references of the Wikipedia article "Robert Todd Lincoln" in English language version.
Undated letter from Mary Harlan Lincoln to Katherine Helm, either held in the "Mary G. Townsend Collection" (Giant in the Shadows: The Life of Robert T. Lincoln by Jason Emerson), or in an unnamed private collection (Swick & McCreary).
Upon the death of George Pullman in 1897, Robert Lincoln, son of Abraham and Mary Lincoln, became president of the Pullman Company. He remained in that position until 1911 when he became chairman of the board. He served in that capacity until 1924 but continued to serve on the board until his death in 1926.
as anxious as you can be to have every liberty & privilege restored
Robert Todd Lincoln, son and the last survivor of the family of President Lincoln, died peacefully at Hildene, his Summer home, last night. His death was discovered by a servant, who went as usual to call Mr. Lincoln to breakfast. Dr. C.M. Campbell of Manchester Centre, the family physician, declared death due to cerebral hemorrhage induced by arterio-sclerosis.